Seven patients with inactive ulcerative colitis and seven patients with Crohn's disease (5 inactive, 2 mildly active) received interferon treatment for associated chronic active hepatitis. Neither relapse (except in one patient) nor worsening of the clinical course of the inflammatory bowel disease was observed during treatment. According to these results chronic active hepatitis associated with inflammatory bowel disease can be treated with interferon without the risk of deteriorating the course of the inflammatory bowel disease.